Since the discovery of carbon nanotubes (CNTs) in 1991, CNTs have been used in various fields including energy storage, molecular electronics, nanoprobes, sensor, and composite materials. The excellent mechanical, electrical, and thermal properties of CNTs have also led to the emergence of CNTs as electrocatalysts, either as a stand-alone electrode with the necessary binder or as additionally modified with metal centers with added binders. CNT sheets have been prepared that are flexible, stackable with multi-layers, reusable, much lighter than metal, and are conductive.
However, CNTs are still challenged with the controllability in alignment-dependent, interconnection-dependent, and layered thickness-dependent electrical conductivity. Although it has been shown that chemical vapor deposition (CVD) can be used to fabricate CNT arrays (see for example, Jakubinek, M. B., Johnson, M. B., White, M. A., Jayasinghe, C., Li, G., Cho, W., Schulz, M. J., and Shanov. “Thermal and electrical conductivity of array-spun multi-walled carbon nanotube yarns.” Carbon 50, no. 1 (2012): 244-248), it is challenging to fabricate low resistance and thin layer CNT sheets. Specific challenges include: 1) handling CNT sheets, in particular for cutting, bonding, and electrically connecting the sheets, and 2) transporting CNT sheets from one place to other without damaging them.